Offense in the NFL is all about identifying mismatches and exploiting them, something the New England Patriots were able to do on a weekly basis when they had tight ends Rob Gronkowski and Aaron Hernandez.

Gronkowski was an in-line monster for the Patriots before blowing out his knee two weeks ago, stomping all over secondaries that couldn’t match his rare blend of size, strength and body control. Before going to prison, Hernandez was their joker, lining up at a bunch of different spots, from the backfield to out wide.

Now that those two are out of the picture, the Patriots are using versatile running back Shane Vereen, a second-round draft pick two years ago, to keep opponents on their heels in the passing game. Vereen has caught 36 passes for 323 yards and a touchdown since returning from a wrist injury five weeks ago.

“Since they don’t have as many tight ends as they have had in the past, they kind of use the running back in the same fashion, [though] not necessarily the same routes,” Ravens defensive coordinator Dean Pees said. “He’s just another weapon for them.”

While Vereen had a quiet game in last week’s loss to the Miami Dolphins, Patriots quarterback Tom Brady likes to target Vereen as a route-runner out of the backfield and the team also designs screen passes for him. The Patriots also will move him out to play receiver, hoping to get him matched up with a linebacker or a safety in space.

Darren Sproles of the New Orleans Saints and Danny Woodhead of the San Diego Chargers, whom Vereen has replaced in New England, are the only running backs who have averaged more yards per route run this season, according to Pro Football Focus.

To put it in perspective, Vereen’s 2.08 yards per route run are better than every Ravens wide receiver, including Torrey Smith, who is averaging 1.80 per route.

“He’s such a dynamic receiver out of the backfield,” Pees said. “It’s kind of like last week with Detroit when you had [running back Reggie] Bush. The guy is a very good runner but they put him out in an empty formation and get a linebacker matched up on him -- that’s a bad deal.”

In New England’s comeback win over Cleveland two weeks ago, Vereen had a 50-yard reception when he lined up wide left and ran a go route past Browns inside linebacker Craig Robertson. Moments later, Vereen lined up in the backfield next to Brady, who was in the shotgun, and took an inside handoff six yards for a touchdown.

The Patriots shuffle through their running backs like a Las Vegas card dealer, but the Ravens can expect to see Vereen in the red zone and when the Patriots use their no-huddle offense. They haven’t been pushing pre-snap speed limits like they did a year ago, but they still are capable of catching defenses off guard with quick snaps.

Vereen has averaged five yards per carry on 40 rushing attempts this season and is capable of breaking a big one at any time, but the way the Patriots use him as a receiving threat reminds some Ravens players of Bush and Sproles.

“They like to move them around, get them out in space,” defensive end Chris Canty said. “They will give him the ball in the backfield but they like to throw it to him a lot. He’s a very versatile player. He’s a burner. He’s got real speed out there so we have to be aware of where he is at all times.”